He separated flowering from flowerless plants, and divided the former into Dicotyledons and Monocotyledons.
The plant world falls into two great divisions, the higher or flowering plants (Phanerogams), characterized by the formation of a seed, and the lower or flowerless plants (Cryptogams), in which no seed is formed but the plants are disseminated by means of unicellular bodies termed spores.
Each class of flowerless or cryptogamic plants requires special treatment for the herbarium.
ACOTYLEDONES, the name given by Antoine Laurent de Jussieu in 1789 to the lowest class in his Natural System of Botany, embracing flowerless plants, such as ferns, lycopods, horse-tails, mosses, liverworts, sea-weeds, lichens and fungi.
Flowering plants bear a seed containing an embryo, with usually one or two cotyledons, or seed-leaves; while in flowerless plants there is no seed and therefore no true cotyledon.
The apparently clear distinction between flowering and flowerless plants has been broken down by the series of gradations between the two exhibited by the Lycopodiaceae, Rhizocarpeae, and Gymnospermeae.
Summer sees the lotus (renge) convert wide expanses of lake and river into sheets of white and red blossoms; a comparatively flowerless interval ensues until, in October and November, the chrysanthemum arrives to furnish an excuse for fashionable gatherings.